1. Field of the Invention
This invention relates generally to therapeutic beds, and more particularly to an improved rotating bed capable of placing a patient in a prone position.
2. Description of the Related Art
Various types of therapeutic supports for bedridden patients have been well known for many years. For example, such therapeutic supports include but are not limited to low air loss beds, fluidized bead beds, and patient positioning beds. Patient positioning has been used in hospital beds for some time to enhance patient comfort, prevent skin breakdown, improve drainage of bodily fluids, and facilitate breathing. One of the goals of patient positioning has been maximization of ventilation to improve systematic oxygenation. Various studies have demonstrated the beneficial effects of body positioning and mobilization on impaired oxygen transport. The support of patients in a prone position can be advantageous in enhancing extension and ventilation of the dorsal aspect of the lungs.
One type of prone positioning bed comprises a base frame, a patient support platform rotatably mounted on the base frame for rotational movement about a longitudinal rotational axis of the patient support platform, and a drive system for rotating the patient support platform on the base frame. Such therapeutic beds are described in international patent applications having publication numbers WO 97/22323 and WO 99/62454. This type of bed is particularly advantageous for the treatment of patients with severe respiratory problems. Preferably, as described in publication number WO 99/62454, each end of the bed has a central opening at or near the longitudinal rotational axis of the patient support platform for efficiently managing the numerous patient care lines that are generally necessary for treating a patient on the patient support platform.
In the therapeutic bed of WO 99/62454, the central opening for receiving patient care lines at the head of the bed is provided by a continuous upright end ring, which also serves as a means for rotatably mounting the patient support platform on rollers. One drawback of such an arrangement is that the continuous end ring obstructs access to the head of the patient. Additionally, the initial placement of a patient on the bed requires disconnection of all patient care lines, and to remove a patient care line from the end ring requires that one end of the patient care line be unplugged from either the patient or the piece of equipment to which the line is attached, which can be very inconvenient and may jeopardize the patient, depending on the particular condition of the patient.
To retain a patient on the patient support platform in the prone position, the bed of WO 99/62454 has a pair of side rails fixedly mounted to the patient support platform in an upright position using stanchions and complementary sockets. A plurality of patient support packs are pivotally mounted on the side rails, and associated straps are buckled over the patient to hold the patient in place. Although the patient support packs may be flipped to the outside of the bed to uncover the patient in the supine position, the side rails remain upright and thus obstruct access to the patient in the supine position. To improve access to the patient in the supine position, it would be desirable to be able to move the side rails completely out of the way without removing them from the bed. Also, it would be advantageous to have a reliable way to ascertain whether the straps that buckle over the patient are properly tensioned to support the patient prior to moving the patient to the prone position.
One of the problems in the art of prone positioning therapeutic beds is to provide electrical connections to the bed for both the power and controller equipment that moves the bed and for the patient monitoring systems on the bed. To allow unrestricted rotation of the bed of WO 99/62454, electrical power has been provided by wire brushes at the interface between the rotating part of the bed and the nonrotating part of the bed. However, due to vibration and other abrupt movements, such wire brushes cause problems of electrical intermittence, which can be detrimental to the therapy of the patient. A direct, wired electrical connection would be preferable to eliminate such intermittence, provided that the wired electrical connection is capable of articulation during movement of the rotating part of the bed into the prone position.
Another problem in the field of prone positioning beds is to sufficiently support the head of a patient during rotation. In the past, elastic straps have been stretched across the patient""s head to secure the head to the patient support platform. However, such straps are generally uncomfortable for the patient and do not provide sufficient lateral support for the patient""s head. Additionally, such straps do not provide sufficient adjustability. It would be a significant improvement to provide a comfortable, adjustable head restraint that supports the patient""s head both laterally and vertically.
Typically, prone positioning beds have lateral support pads for supporting the sides of the patient during rotation. It is known in the art for such lateral support pads to be laterally adjustable. For purposes of rotational stability, it is desirable for the patient to be centered on the patient support platform. Therefore, it would be an advancement in the art to provide adjustable lateral support pads that automatically center the patient on the patient support platform. In conjunction with automatically centering lateral support pads, it would also be an advancement to provide symmetric leg adductors/abductors.
As mentioned above, prone positioning beds preferably have a drive system for rotating the patient support platform on the base frame. However, such drive systems generally prevent manual rotation of the patient support platform by medical personnel. If a patient develops an emergency condition, such as the need for CPR, while the bed is in a position other than the 0xc2x0 flat supine position, the drive system must be used to rotate the bed back to the 0xc2x0 supine position before administering appropriate care to the patient. Because the drive systems are subject to mechanical and electrical failures, it would be advantageous to provide a back-up means for quick, manual rotation of the patient support platform in emergency conditions.
Prone positioning beds also preferably have a locking mechanism to lock the patient support platform in a desired rotational position. One known locking mechanism comprises a lock pin longitudinally mounted in the base frame that is insertable into a corresponding hole on the patient support platform. However, such lock pins may be jostled loose under the influence of vibration and other abrupt movements of the bed. It would be an improvement to provide a means to prevent such accidental disengagement of the lock pin.
It is also known in the art of prone positioning beds to provide a sensor for determining and controlling the rotational position of the patient support platform. As taught in WO 99/62454, the rotational position of the patient support platform may be monitored and controlled by a rotary opto encoder of the type described therein. However, such a rotary opto encoder is fairly cumbersome and must be reinitialized by moving to an index location in the event of power interruptions. It would be more desirable to provide a simple and reliable sensor that determines angle positioning relative to a fixed reference to control the rotational position of the patient support platform.
A therapeutic bed in accordance with the present invention is directed to solving the aforementioned problems. The bed is a prone positioning bed comprising a base frame, a patient support platform rotatably mounted on the base frame for rotational movement about a longitudinal rotational axis of the patient support platform, and a drive system for rotating the patient support platform on the base frame. An upright end ring at the head end of the bed is split into an upper section and a lower section. The upper section is removable from the lower section to allow improved access to the head of the patient and to allow placement or removal of the patient from the bed by removal of patient care lines from the end ring without removing the patient care lines from the patient or the equipment to which the lines are attached. Likewise, at the foot end of the bed, an opening is provided that is of sufficient size to permit passing of various patient connected devices, such as foley bags, through the opening without disconnecting the devices from the patient. Additionally, the bed is provided with pivotally mounted side rails that may be folded neatly out of the way underneath the patient support platform for improved access to the patient in the supine position. Straps are provided to secure the opposing side rails over the patient before rotation into the prone position. Preferably, a pressure-sensitive tape switch is mounted on the patient support platform adjacent each side rail. When the side rail straps are properly tensioned, the side rails engage the tape switches, which allows the patient support platform to be rotated into the prone position. Alternatively, the straps that secure the opposing side rails over the patient may be connected to the patient support platform with tension-sensitive strap connectors that provide an indication of whether the straps are sufficiently tensioned before the patient is rotated into the prone position. The tension-sensitive strap connectors provide both a visual indication and an electrical signal that may be used by a controller to control the rotation of the patient support platform.
The present invention also incorporates a direct, wired electrical connection to the patient support platform while still allowing full rotation of the patient support platform in either direction. The necessary electrical wires are housed within a chain-like cable carrier that is disposed within an annular channel attached to the patient support platform. An annular cover is installed adjacent the annular channel to retain the cable carrier within the annular channel, but the annular cover is not attached to the annular channel. Rather, the annular cover is attached to the nonrotating part of the bed. One end of the cable carrier is attached to the annular channel, and the other end is attached to the annular cover. The length of the cable carrier is sufficient to allow a full 360xc2x0 rotation of the patient support platform in either direction from 0xc2x0 supine flat while maintaining a direct electrical connection.
More preferably, the direct, wired electrical connection to the patient support platform may be provided with a flexible printed circuit board (PCB) in lieu of a chain-like cable carrier. The flexible PCB resides within an annular channel attached to the patient support platform, and an annular cover is fastened to a flange of the annular channel such that a gap exists between the annular channel and the annular cover around the outer periphery. One end of the flexible PCB is attached to the annular channel, which provides power and electrical signals to the rotating part of the bed, and the other end of the flexible PCB passes through the gap between the annular channel and the annular cover and is connected to the electrical apparatus on the nonrotating part of the bed. Like the cable carrier mentioned above, the flexible PCB has a length sufficient to allow a full rotation of the patient support platform in either direction while maintaining a direct electrical connection between the nonrotating and rotating parts of the bed. To ensure that the wired electrical connection is not articulated beyond its physical limit as a result of manually rotating the bed in the emergency backup mode, a mechanical stop is provided to limit rotation of the patient support platform to about 365xc2x0. Sensors are provided to detect activation of the mechanical stop.
The present therapeutic bed also includes a pair of adjustable head restraints. Each head restraint, which is slidably mounted on transverse rails of the patient support platform, includes a clamping mechanism that fixes the position of the head restraint both vertically and laterally through the operation of a single lever. Each head restraint includes a pad that comfortably supports the front and side of the patient""s head.
A therapeutic bed in accordance with the present invention further includes a pair of symmetrically mounted lateral support pads that serve to automatically center the patient on the patient support platform. The lateral support pads are symmetrically mounted to a threaded rod that is transversely mounted to the patient support platform. The threaded rod has right-hand threads on one side and left-hand threads on the other side. One of the lateral support pads is mounted to the right-hand threaded portion of the threaded rod, and the other lateral support pad is mounted to the left-hand threaded portion of the threaded rod. By rotating the threaded rod in the desired direction, the lateral support pads may be moved symmetrically toward or away from the patient. Similarly, a preferred bed also includes a pair of leg adductors/abductors that are mounted with a threaded rod in like manner as the lateral support pads.
The present therapeutic bed also preferably has a quick release mechanism for manually disengaging the patient support platform from the drive system. The quick release mechanism preferably comprises a manually operable lever and linkage that cooperate to push and pull a shaft to which a roller is mounted. The roller may thus be brought into or out of engagement with the belt of the drive system. When the roller is disengaged from the drive belt, the patient support platform may be manually rotated, which is useful in emergency conditions such as CPR.
The present bed further includes a lock pin mounted to the base frame that is insertable into a cooperating hole of a locking ring on the patient support platform to mechanically prevent rotation of the patient support platform. Preferably, the lock pin assembly incorporates a detent and a pair of proximity switches that indicate the position of the lock pin with respect to the locking ring and electrically control whether the patient support platform is allowed to rotate. The lock pin may be twistable to engage a protrusion on the lock pin with the patient support platform and thereby prevent retraction of the pin from its locked position.
The present invention also preferably includes an electrical angle sensor mounted to the patient support platform. A preferred angle sensor comprises an inclinometer that is sensitive to its position with respect to the direction of gravity. The output signal from the angle sensor may be calibrated for a controller of the drive system to control the rotational position of the patient support platform.
It is an object of the present invention to provide a therapeutic bed having a split end ring at the head of the bed for improved access to the head of a patient lying on the bed and for placement or removal of the patient from the bed without disconnecting patient care lines from the patient.
It is another object of this invention to provide an opening at the foot of the bed having sufficient size to permit passing of patient connected devices, such as foley bags, through the opening without disconnecting the devices from the patient.
It is a further object of the present invention to provide a therapeutic bed having side rails that fold underneath the patient support platform of the bed for improved bedside access to the patient.
It is yet another object of this invention to provide a therapeutic bed with patient retaining straps having strap connectors that indicate whether the straps are sufficiently tensioned.
It is another object of the present invention to provide a therapeutic bed with side rails that are engageable with pressure-sensitive tape switches mounted to the patient support platform to indicate whether the straps on opposing side rails are properly tensioned.
It is still another object of this invention to provide a prone positioning therapeutic bed having a direct, wired electrical connection between the rotating part of the bed and the nonrotating part of the bed.
It is yet another object of this invention to mechanically limit rotation of the bed in either direction to one full 360xc2x0 turn plus about 5xc2x0, and to electrically detect when one full turn has been reached.
It is a further object of this invention to provide a prone positioning therapeutic bed having a head restraint with a clamping mechanism that fixes the position of the head restraint both vertically and laterally through the operation of a single lever.
It is yet another object of this invention to provide a therapeutic bed having a pair of symmetrically mounted lateral support pads that serve to automatically center the patient on the patient support platform.
It is still another object of this invention to provide a prone positioning therapeutic bed with a patient support platform, a drive system for rotating the patient support platform, and a quick release mechanism for manually disengaging the patient support platform from the drive system to allow manual rotation of the patient support platform.
Another object of this invention is to provide a prone positioning therapeutic bed having a locking pin for mechanically preventing rotation of the patient support platform as desired.
Still another object of this invention is to provide a prone positioning therapeutic bed having a locking pin with cooperating proximity switches for electrically preventing rotation of the patient support platform as desired.
A further object of this invention is to provide a rotating therapeutic bed having a locking pin that is twistable to prevent disengagement of the locking pin.
Yet another object of this invention is to provide a therapeutic bed having a rotatable patient support platform with gravity-sensitive angle sensors for controlling the rotation of the patient support platform and for determining the longitudinal (Trendelenburg) angle of the patient surface.